House Oversight and Government Reform Committee Chairman Darrell Issa accused the IRS of being “maliciously self-indulgent” by spending about $49 million on conferences between 2010 and 2012.

The California Republican said IRS employees were effectively “guilty of tax evasion” because they paid no taxes on perks they received at events and called for wholesale changes at the embattled agency.

“Americans have the right to know that the money Washington takes from them through the IRS is well-spent,” he said.

The IRS is responding to outrage over excessive spending at the same time it is grappling with the fallout of a tea-party-targeting program that has engulfed the agency in scandal.

Several IRS officials were in the hot seat today after a Treasury inspector general report highlighted the big conference spending by making a case study of a 2010 agency event in Anaheim, Calif. The IRS spent $17,000 to pay a keynote speaker at that conference whose specialty was painting unique pictures of celebrities such as Michael Jordan and Bono. The agency spent another $50,000 on a training video that parodied “Star Trek.”

Faris Fink, the commissioner of the IRS division that ran the conference, played the role of Spock in the spoof and is among the agency officials testifying before Issa’s committee Thursday. He told panel members he was sorry the video was produced.

“It is embarrassing, and I apologize,” he said. “I regret the fact they were made.”

Still, the “Star Trek” video was roundly ridiculed by lawmakers.

Maryland Rep. Elijah Cummings, the top Democrat on the Oversight Committee, said he was stunned to learn how much money the IRS spent on the video.

“I live on a block where most people don’t even make $50,000 a year,” he said. “But yet we can make a video that has no redeeming value — none.”

Acting IRS Commissioner Daniel Werfel has criticized the spending and said the agency’s culture is changing.

“While there were legitimate reasons for holding the meeting, many of the expenses associated with it were inappropriate and should not have occurred,” Werfel said. “Taxpayers should take comfort in knowing that these kinds of expenses are no longer permitted and such a conference would not take place today.”

He described to lawmakers his plans to help reform the agency, including working to cooperate with congressional investigations, re-examine the regulations of nonprofits and a possible restructuring of the IRS — depending on what he uncovers during his 30-day review.

Issa also pledged to help Werfel potentially speed the firing process for agency employees. IRS employees now can appeal their terminations for years and still collect a government paycheck, and both Werfel and Issa said the process should be speedier.

The IRS is making the case that it has dramatically cut costs related to conferences. The agency said it spent less than $4.9 million in fiscal year 2012 on large conferences, compared to the $37.6 million spent two years earlier.

Still, the new IRS chief — on the job since May 22 — is taking swift disciplinary action. He said Wednesday that he placed two agency officials on leave in response to potentially improper behavior at a conference.

Fred Schindler, the director of implementation oversight at the IRS’s Affordable Care Act office, and Donald Toda, a California-based employee, are accused of accepting about $1,100 in free food and gifts at the Anaheim conference.

Issa said he expects his panel to interview Schindler and Toda. The chairman praised Werfel’s response to the conservative targeting and the conference spending, saying that the acting commissioner has been responsive to congressional inquires. Issa said Werfel has called him to keep the chairman apprised of the actions he’s taken within the IRS to hold employees accountable.

Still, Fink wasn’t spared from blistering critiques from lawmakers. Rep. Jason Chaffetz (R-Utah) slammed Fink for being unable to tell lawmakers when it first occurred to him that the conference was an inappropriate use of taxpayer money.

“You can’t even tell me when you thought this was wrong,” Chaffetz quipped.

Rep. Mark Meadows (R-N.C.) said Fink’s apology was “hollow.”

And Rep. Trey Gowdy (R-S.C.) emotionally called the conference spending a “moral issue” when recounting a story about a struggling single mother who worked for him as a secretary in South Carolina and had to ask to borrow money to purchase a birthday present for her child around the same time the IRS was hosting its lavish conference.

When asked by Chaffetz when he first learned of the cost of the California event, Fink said he was not involved with the planning of the event and did not learn “until much later.”

But Fink later added that he signed paperwork authorizing the event.

Issa — who said he was not attempting to “trap” Fink — expressed worries that Fink may have perjured himself.

“If I heard correctly, you answered you were not aware of the cost of these,” Issa said. Greg Kutz, an assistant Treasury inspector general, “made it clear you signed a routing slip. You attended briefings. Would you like to revise your statement?” Fink then responded that he did in fact know the event’s cost.

“I was aware of the cost, the estimated cost of $4.3 million, when we did the briefing for the two deputy commissioners,” Fink said in response. “That’s when I became aware.”

The hearing served as an awkward reunion of sorts between Kutz and Issa. Kutz wrote a 2010 report on for-profit colleges while at the Government Accountability Office.

Issa derided the study’s methodology as biased and faulty, and Kutz was eventually replaced as the head of the GAO’s forensic auditing division and moved to the Treasury’s inspector general office, where he provided key details today to assist the committee’s investigation.

CORRECTION: An earlier version of this report misspelled the name of Greg Kutz, an assistant Treasury inspector general.